Add FMF management to common fp intrinsics in GlobalIsel
Summary: This the initial code change to facilitate managing FMF flags from Instructions to MI wrt Intrinsics in Global Isel. Eventually the GlobalObserver interface will be added as well, where FMF additions can be tracked for the builder and CSE.
Reviewers: aditya_nandakumar, bogner
Reviewed By: bogner
Subscribers: rovka, kristof.beyls, javed.absar
Differential Revision: https://reviews.llvm.org/D55668